The present invention generally relates to the mixture of Low Volume Reticles (LVRs) with High Volume Reticles (HVRs) for the processing of gate arrays, embedded arrays and rapid chip products.
A number of problems have been identified in the fields of reticle technology, photolithography and array-based ASICS. One such problem is the need for high volume production of master device templates that can be customized into several low volume products using customer specific reticles. Another problem is the need for Low Volume, customer specific, Reticles (LVRs) which consist of multiple device layers on a single reticle to be used concurrently in production with High Volume Reticles (HVRs) which consist of multiple instances of a single device layer on a reticle. Still another problem is the need for a pattern of the LVRs to register to the HVRs when printed on the wafer. Conversely, another problem is the need for a pattern of the HVRs to register to the LVRs when printed on the wafer. Yet another problem is the decrease in die per wafer due to wrapping a scribe around each die for both LVRs and HVRs for registration and end of line testing. Still another problem is the high cost of standard HVR sets relative to an LVR set custom order. Another problem is the prototype turnaround time of wafer processing associated with full LVR sets.
There are two known existing solutions to these problems, namely, using a full set of LVRs or using a full set of HVRs, without mixing HVR and LVR in a single set. There are deficiencies, however, with both of these solutions.
Traditional device manufacturing makes use of HVRs that consist of multiple instances of a single layer each reticle in the set. FIG. 1 shows a first HVR reticle 50 and a second HVR reticle 52. The first HVR reticle 50 has an array of die of a first layer data 54a. The array of die of the first layer data 54a is formed in a square pattern, in this case in a 2×2 array. An X scribe 56a is positioned below the first layer data 54a and a Y scribe 58a is positioned to the right of the first layer data 54a. Similarly, the second HVR reticle 52 has an array of die of a second layer data 54b. The second layer data 54b is formed in a square pattern identical to that of the first layer data 54a. An X scribe 56b is positioned below the second layer data 54b and a Y scribe 58b is positioned to the right of the second layer data 54b. 
The first layer data 54a is repeated in multiple instances on each reticle 50, such that when printing to the wafer 60, as illustrated in FIG. 2, multiple chips are made per exposure.
The X scribes 56a, 56b and the Y scribes 58a, 58b are used for registration when exposing the reticle 52 to the wafer 60. As illustrated in FIG. 3, the first layer data 54a was first exposed on the wafer 60. The X scribe 56b of the second layer data 54b then aligns to the X scribe 56a of the first layer data 54a, and the Y scribe 58b of the second layer data 54b then aligns to the Y scribe 58a of the first layer data 54a around each exposure and to create scribeline devices for electrical testing at sort.
This method of using a full set of HVRs provides for high speed manufacturing since multiple instances of the devices are exposed simultaneously on the wafer 60. However, it requires that one reticle be created for each layer of the device. This method makes small customer orders economically unfeasible due to the high cost of a reticle set for a device which consists of many layers.
The other method of using a full set of LVRs also has its problems. The traditional LVR approach makes use of reticles which have multiple device layers, greatly reducing the size of the reticle set. An LVR reticle 62 is illustrated in FIG. 4. The LVR reticle 62 has a first layer data 64a, a second layer data 64b, a third layer data 64c, and a fourth layer data 64d. Each layer data 64a, 64b, 64c, 64d has an X scribe 66 positioned therebelow and a Y scribe 68 positioned to the right thereof.
Rather than expose the whole reticle field, the stepper file blades off all but one region or layer data 64a, 64b, 64c, 64d of the reticle 62 and one layer data is printed at a time, as illustrated in FIG. 5. A second region or layer data 64a, 64b, 64c, 64d of the reticle 62 is then used to print the next layer of the device, as illustrated in FIG. 6.
The method of using a full set of LVRs reduces reticle costs which makes it ideal for small scale custom orders. However, the production time increases significantly due to only exposing one instance of a layer at a time. For large scale production, this method is lacking because of the high cycle time impact.